U.S. Pat. No. 4,625,712 and U.S. patent application Ser. No. 07/124,560 disclose expendable miniature axial flow blood pumps adapted to be percutaneously inserted into the human vascular system for emergency cardiac assit purposes. Although these pumps have been quite successful in practice, there is a continuing need for reduction in size (e.g. in order to allow insertion through a standard large-diameter needle rather than through a surgical incision) as well as for improved ruggedness, reliability and ease of handling (e.g. in order to allow use by less skilled personnel), all at lesser cost.